Celovito obvladovanje precizijskega litja z uporabo trajnih vložkov : magistrsko delo

Mrvar, Jakob (avtor), Petrič, Mitja (mentor)

V magistrskem delu z naslovom Celovito obvladovanje precizijskega litja z uporabo trajnih vložkov je predstavljena metodologija precizijskega litja, od načrtovanja procesa v virtualnem svetu, izdelave iztaljivega modela, izgradnje keramične školjke in litja. Obravnavana je tehnična problematika uporabe mehansko predobdelanih trajnih vložkov, ki se kot jedro vstavijo v ležišče voščenega ali 3D natisnjenega modela, pri čemer slednji sloni na enem jedrnem nastavku. Le-ta je nato togo vpet v keramiko, po izvedenem sintranju pa ga v livni votlini oblije talina, ki tvori po končanem strjevanju in ohlajanju tesen krčni ujem zaradi nakrčevanja ulivane zlitine na vložek. Konstruiran ulitek je bil celovito obravnavan po virtualni in eksperimentalni poti. V delu je predstavljena metodologija in tehnike izračunov livarskih procesov s fokusom na usmerjeno strjevanje, nastanek livarskih napak in razvoja notranjih napetosti in deformacij in dimenzijsko natančnost za doseganje kakovostnih zahtev po laboratorijski eksperimentalni poti. Ugotovljeno je, da se izvedeni izračuni samostojnih strjevalnih področij dobro skladajo z eksperimentalno RTG analizo makro strukture. Dimenzije ulitka so ustrezne, notranje napetosti na površini ulitka izmerjene z uklonsko rentgensko analizo (XRD) pa so od -3 MPa do 43 MPa, kar je blizu izračunanim vrednostim. Na mestu krčnega naseda med vložkom in ulivano zlitino AlSi10Mg pride do kakovostnega tesnega ujema. Tehnika premazovanja mehansko obdelane navojnice s cirkonskim premazom pa se je izkazala kot dobra implementirana tehnična rešitev. Ugotovljeno je, da je pozicioniranje vložka v školjki natančno, ko je 3D tiskani model v natančnem tesnem ujemu z vložkom še pred izdelavo keramične školjke. V delu postavljena metodologija in same tehnike načrtovanja predstavljajo celovit kakovostni model za hitro izdelavo prototipov, ki je prenosljiv in pomemben tudi za serijsko proizvodnjo z uporabo precizijskega litja kot izdelovalne tehnike.

• Jezik: Slovenski jezik
• Ključne besede: precizijsko litje, ulivno-napajalni sistem, izračun livarskih procesov, vložek, 3D optično skeniranje, RTG, XRD
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: NTF - Naravoslovnotehniška fakulteta
• Kraj izida: Ljubljana
• Založnik: J. Mrvar
• Leto izida: 2023
• Št. strani: XV, 43 f.
• PID: 20.500.12556/RUL-150045
• UDK: 669
• COBISS.SI-ID: 167125251
• Datum objave v RUL: 13.09.2023

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Comprehensive mastery of investment casting using permanent inserts : master's thesis

Izvleček

In the Master's thesis titled "Comprehensive Management of Investment Casting Using Permanent Inserts", a methodology for investment casting is presented, ranging from process planning in the virtual world, to the creation of the expendable model, the construction of the ceramic shell, and finally the casting process itself. The technical issues surrounding the use of machined permanent inserts are addressed. These inserts serve as a core that is placed in the cavity of a wax or 3D-printed model, which in turn rests on a single core pin. This core pin is then rigidly embedded in the ceramic after sintering. Subsequently, the core is partially enveloped by molten metal in the casting cavity, resulting in a tight shrink-fit due to the alloy’s contraction around the insert after solidification and cooling. The designed casting was comprehensively examined through both virtually and experimentally. The study presents the methodology and computational techniques focused on directional solidification, the formation of casting defects, the development of internal stresses and deformations, and dimensional accuracy to meet quality requirements through laboratory experimentation. It was found that the calculated individual solidification zones align well with the experimental X-ray radiography (RTG) analysis of the macrostructure. The dimensions of the casting are appropriate, and the internal stresses on the surface of the casting, measured by X-ray diffraction (XRD), range from -3 MPa to 43 MPa, which is close to the calculated values. At the site of the shrink-fit between the insert and the cast AlSi10Mg alloy, a high-quality tight fit is achieved. The technique of coating the mechanically treated thread with a zirconium coating proved to be a good technical solution. It was determined that the positioning of the insert in the shell is accurate when the 3D-printed model has a precise tight fit with the insert before the ceramic shell is constructed. The methodology and planning techniques presented in the study offer a comprehensive quality model for rapid prototyping, which is transferable and relevant for serial production using investment casting as a manufacturing technique.

• Ključne besede: Investment Casting, Gating-Feeding System, Casting Process Calculations, Insert, 3D Optical Scanning, RTG, XRD